[control-plane] List applying policies in Brokers .status.policies

[creydr]

As the Eventing Authorization feature track describes, target resources of EventPolicies, will reflect in their status, which EventPolicy is applied to them.

For example:

apiVersion: eventing.knative.dev/v1
kind: Broker
metadata:
  name: my-broker
spec:
  ...
status:
  ...
  policies:
    - name: event-policy
      apiVersion: v1alpha1
    - name: another-event-policy
      apiVersion: v1alpha1

  conditions:
    - type: Ready
      status: "True"
    - type: EventPoliciesReady
      status: "True"

As the Broker should support EventPolicies, wee need to do the following:

• Update the Broker reconciler to show applying policies in the Brokers .status.policies and set the Brokers EventPoliciesReady condition. Also watch EventPolicies for changes.
• Set EventPoliciesReady condition to true, in case no policy applies, and set message according to the default-authorization-mode (e.g. Default authorization mode is 'allow-all'). Check the Default Authorization Mode section in the feature track for additional information.

Hint:

• Similar to List applying policies in InMemoryChannel .status.policies knative/eventing#7977

Additional hints for new contributors before starting with this issue:

1. When the issue has the Draft status, the issue is subject to change and thus should not be started to be worked on
2. Make sure you've read and understood the CONTRIBUTING.md guidelines
3. Make sure you're able to run Knative Eventing locally with Knative Eventing Kafka and run at least the unit tests.
4. Feel free to raise any questions you have either directly here in the issue, in the #knative-eventing Slack channel or join the Eventing Workgroup Meeting / Office Hours
5. When you feel comfortable with this issue, feel free to assign it to you (e.g. by commenting /assign). Please be aware that we might unassign you, if we don't see any progress from your side to give other contributors also a chance to work on this issue.

[creydr]

/help
/triage accepted

[knative-prow]

@creydr:
This request has been marked as needing help from a contributor.

Please ensure the request meets the requirements listed here.

If this request no longer meets these requirements, the label can be removed
by commenting with the /remove-help command.

In response to this:

/help
/triage accepted

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.

[creydr]

/assign

[Cali0707]

/area control-plane